1. Field of the Invention
This invention relates to rotary vane devices, sometimes known also as rotary piston machines, where volume changes between vanes, which are working in a cylindrical pressure chamber, are used for a direct pressure to rotary or rotary to pressure power conversion.
2. Description of the Prior Art
It has been recognized since the invention of the steam engine that a more direct energy conversion from pressure to a rotary motion without the use of a reciprocating piston can provide numerous advantages and simplifications in external and internal combustion engines, yet from the hundreds of known variable volume pressure chamber configurations, as best described, classified and tabulated in Felix Wankel's book "Rotary Piston Machines" (Iliffe Books Ltd, London 1963), only Mr. Wankel's "triangular piston" configuration has gained a wide recognition (NSU, Mazda, Curtiss-Wright etc). It was once labeled as "revolutionary significance" because of the following advantages as taken from the Encyclopedia Britannica: small space, low weight to HP ratio, smooth vibrationless operation, quiet running, comparatively low cost and simplicity, no reciprocating parts to minimize inertial and frictional losses, a better heat transfer and no poppet valves are reducing friction and make the fresh charge and exhaust more effective.
In the same book it has also been recognized that the specially classified central-axis cylindrical pressure chamber can provide the highest volumetric throughput besides its relative simplicity, but because of its concentric nature it is also believed that a smooth planetary or cranking arrangement is impossible because a second parallel axis cannot exist. Therefore the existing central-axis configurations in this class are mostly limited to the oscillating type with a stationary vane(s) and an oscillating vane(s) on the output shaft. Basically this is the construction of a rotary actuator with a special porting arrangement adapted to an internally or eternally generated fluid pressure operation, but since the reciprocating linear piston motion is just replaced then by an arcuate oscillating motion, a ratcheting or cranking mechanism still has to be incorporated with little advantage over existing piston machines or engines. One of the oscillating vane internal combustion engine with 4 spark plugs and a rotary flow directing valve is shown in U.S. Pat. No. 5,086
But instead of the oscillating vanes many unidirectional more advantageous variable motion vane devices are in existence where one set of vanes is attached to the uniform motion output shaft while the other set of vanes are on a concentric variable motion shaft. For controlling this motion hard ratchet stops (U.S. Pat. No. 1,003,80 issued to Rodigin 1911), camming arrangements (Tschudi 1927) or more complex gear mechanisms (Kauertz 1960) are used, but the shock loads in all of these arrangements are limiting their operation to slower speeds and shorter life and therefore they have not gained any wider acceptance.
A somewhat different independently centrally pivoting vane arrangement in a cylindrical pressure chamber is found in Keller's U.S. Pat. Nos. 3,748,068 and 3,797,975 where a number of vane guides between adjacent vanes are arranged on an eccentrically rotating disk whose shaft is power rotated for pumping or it will function also as an output shaft when external pressure is applied to variable volume subchambers between the vanes. This arrangement, like most rotary piston machines, has a rather difficult sealing problem and even if its complex vane shaft is mathematically calculated, as shown in U.S. Pat. No. 3,938,918 (J. Snugg and V. Ebrok), the sealing of the vanes still remains a major problem in this configuration besides its incapability for an Otto-cycle operation.
Even in the most successful and know rotary Wankel engine its "sealing grid" still requires 21 individually spring loaded sealing members working in a hard-to-machine epitrochoidal cavity while in the present invention the shape of these sealing members will be simpler and the required number of them is reduced to less than half of that in the Wankel engine.